Add explicit str check on dts path

[ssbb]

It's already a string when it comes from yaml config

[caksoylar]

I think dts_layout in the config gets cast to Path by Pydantic, since it is supposed to be a file path pointing to a dts file: https://github.com/caksoylar/keymap-drawer/blob/main/keymap_drawer/physical_layout.py#L200

This is an example that seems to work as expected:

layout:
  dts_layout: /home/cem/zmk/app/dts/layouts/foostan/corne/5column.dtsi
layers:
  base:
    - A
    - A
    - A
    - A
    - A
    - A
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    - A

Do you actually want to pass the dts file contents as a string in the keymap yaml?

[ssbb]

Gotcha, my bad. I just had older version installed (so via pip and pipx in parallel) which took priority. Looks like it's handled just fine now.